INVESTIGADORES
URBIETA Maria Sofia
congresos y reuniones científicas
Título:
A molecular approach to extremophilic prokaryotic biodiversity in hot springs of a little explored geothermal region in Argentina
Autor/es:
URBIETA, M. S.; GIAVENO, M. A.; GONZALEZ TORIL, E.; DONATI, E
Lugar:
Copenhaguen
Reunión:
Simposio; 14th International Symposium of Microbial Ecology (ISME); 2012
Institución organizadora:
ISME
Resumen:
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Copahue-Caviahue
region is a mountain geothermal area in the northwest of Neuquén
province in Argentina. The whole area is under the influence of
Copahue volcano. The particular geological conditions generated by
the presence of an active volcano favour the presence of many acidic
hot springs and hydrothermal pools. The combination of low pH, high
temperatures, even higher than 90° C, and high metal and sulphur
concentrations make Copahue-Caviahue region an ideal environment for
extremophilic microorganisms to live in. In spite of its uniqueness
and potential, Copahue-Caviahue prokaryotic biodiversity has not been
deeply studied yet. For this first molecular approach to the subject,
water and biofilms samples from hot springs with different pH values
and temperature conditions were collected. Total community genomic
DNA was extracted using commercial kits and 16S rRNA genes were
amplified with general bacteria and archaea primers. Amplicons of
approximately 15000 base pairs were cloned and sequenced. After
careful sequence analysis, polygenetic trees were constructed using
the ARB software. Semicuantitative data was obtained by fluorescence
in situ hybridization (FISH) technique. Firstly hybridizations were
done with general Bacteria
and Archaea
domain probes. Then, considering phylogenetic sequence information,
hybridizations were done with more specific probes. Recounts were
done under the epifluorescence microscope, and it was possible to
calculate total cells numbers for each hot spring, as well as
different taxa percentages.
On
the contrary of what could be expected for extreme conditions as the
ones present in this acidic geothermal area, our study reveals that
biodiversity was quite rich in the hot springs analyzed. We found out
that archaea were the main microorganisms present when pH value was 3
or less and temperature was higher than 36°C. Moreover, when
temperature was higher than 80°C 100% of the clones detected
belonged to Sulfolobales
order, in the Crenarchaeota
phylum. In hot springs where conditions were still acidic but less
extreme, bacteria appear as dominant. By hybridization with specific
probes we detected that Gamma
and Beta-proteobacteria
were the groups better represented, mainly by members of
Acidithiobacillus
and Thiomonas
genus, respectively. Those quimioautotrophic bacteria are common in
acid environments with abundant sulphur compounds. However, in
Copahue-Caviahue hot springs we found as well, many heterotrophic
microorganisms like Pseudomonas
spp.
and primary producers, like members of the Cyanobacteria
phylum. In addition to well characterized bacteria and archaea, many
sequences retrieved were similar to different uncultured clones.
Those sequences are putative candidates for new species not yet
isolated and characterized, and might have new metabolic
characteristics that might help understand interrelations in acidic
hot springs ecosystems.
In
this work we aim to characterize Copahue-Caviahue prokaryotic
biodiversity by non culture techniques, not only to know which
microorganisms inhabit the area, but also in the hope of developing a
model of its geomicrobiology. Besides, it is of great interest the
possibilities of detecting, and in the future, isolating,
microorganisms with particular metabolic characteristics that might
be used in new biotechnological processes.